Chemical Clue to 'Popcorn Workers Lung'

Aug. 31, 2007 -- Scientists have new clues about the roots of a rare, life-threatening lung disease called bronchiolitis obliterans in workers in the flavor industry.

Bronchiolitis obliterans is a form of fixed obstructive lung disease, an irreversible condition which makes it difficult for air to flow out of the lungs.

A new European study suggests that workers in flavor factories who get excessive exposure to a butter-flavor chemical called diacetyl may be particularly likely to develop bronchiolitis obliterans, or "popcorn workers lung," as the condition is sometimes called.

The researchers included Frits van Rooy, MD, of the environmental epidemiology division of the Institute for Risk Assessment Sciences, located in the Dutch city of Utrecht.

They interviewed and gave checkups (including lung function tests) to some 200 people who had worked at a chemical plant that makes diacetyl in the Netherlands.

People with suspected bronchiolitis obliterans got additional lung tests. A total of four people were found to have bronchiolitis obliterans.

All of those workers had worked directly with diacetyl. Three of them were nonsmokers.

The researchers can't rule out the possibility that other chemicals -- or other factors -- may have caused those cases of bronchiolitis obliterans. But van Rooy and colleagues argue that diacetyl appears to be a likely factor.

This isn't the first time that diacetyl has been linked to popcorn workers lung. In April, the CDC reported seven cases of the disease at four California flavor factories between 2002 and 2006.

The CDC notes no known risk to consumers from diacetyl or other flood flavorings.

The Dutch cases are the first reports of the condition in European flavor factories, according to van Rooy and colleagues.

Their study doesn't show whether the Dutch flavor factory had adequate ventilation or other appropriate conditions.

An editorial accompanying van Rooy's report states that although diacetyl's hazards aren't in question, "uncertainties do remain."

However, "the collective evidence for diacetyl causing a respiratory hazard supports action to minimize exposure to diacetyl [in workers], even if contributions by other flavoring chemicals exist."

That editorial comes from Kathleen Kreiss, MD, of the U.S. National Institute for Occupational Safety and Health (NIOSH).

The study and editorial appear in the American Journal of Respiratory and Critical Care Medicine.